ICSE Class 10 Chemistry Previous Year Question Paper 2020

Q 1.

(a) Choose the correct answer from the options given below:

(i)The element with the highest ionisation potential is

1. Hydrogen
2. Caesium
3. Radon
4. Helium

 

(ii) The inert electrode used in the electrolysis of acidified water is

1. Nickel
2. Platinum
3. Copper
4. Silver

 

(iii) A compound with a low boiling point is

1. Sodium chloride
2. Calcium chloride
3. Potassium chloride
4. Carbon tetrachloride

 

(iv) The acid which can produce carbon from cane sugar is

1. Concentrated hydrochloric acid
2. Concentrated nitric acid
3. Concentrated sulphuric acid
4. Concentrated acetic acid

 

(v) The organic compound having a triple carbon–carboncovalent bond is

1. C₃H₄
2. C₃H₆
3. C₃H₈
4. C₃H₁₀

 

(b) State the relevant observationfor each of the following reactions:

1. Action of concentrated nitric acid on copper.
2. Addition of excess ammonium hydroxide to copper sulphate solution.
3. A piece of sodium metal is put into ethanol at room temperature.
4. Zinc carbonate is heated strongly.
5. Sulphide oreis added to a tank containing oil and water, and then stirred or agitated with air.

 

(c) Write a balanced chemical equation for each of the following:

1. Reaction of carbon powder and concentrated nitric acid.
2. Reaction of excess ammonia with chlorine.
3. Reaction of lead nitrate solution with ammonium hydroxide.
4. Producing ethane from bromoethane using Zn/Cu couple in alcohol.
5. Complete combustion of ethane.

 

(d)

(i) Draw the structural formula for each of the following:

1. 2,2 dimethyl pentane
2. Methanol
3. Isopropane

 

(ii) Write the IUPAC name for the following compounds:

1. acetaldehyde
2. acetylene

 

(e) State one relevant reason for each of the following:

1. Graphite anode is preferred to platinum anode in the electrolysis of molten lead bromide.
2. Soda lime is preferred to sodium hydroxide in the laboratory preparation of methane.
3. Hydrated copper sulphate crystals turn white on heating.
4. Concentrated nitric acid appears yellow when it is left for a while in a glass bottle.
5. Hydrogen chloride gas fumes in moist air.

 

(f) Calculate:

1. The amount of each reactant required to produce 750 ml of carbon dioxide when two volumes of carbon monoxide combine with one volume of oxygen to produce two volumes carbon dioxide.2CO + O₂⟶ 2CO₂
2. The volume occupied by 80 g of carbon dioxide at STP.
3. Calculate the number of molecules in 4.4gm of CO₂.[Atomic mass of C=12, O=16]
4. State the law associated in question no.(f)(i) above.

 

(g) Give one word or a phrase for the following statements:

1. The chemical bond formed by a shared pair of electrons, each bonding atom contributing one electron to the pair.
2. Electrode used as the cathode in the electro-refining of impure copper.
3. The substance prepared by adding other metals to a base metal in appropriate proportions to obtain certain desirable properties.
4. The tendency of an atom to attract electrons to itself when combined in a compound.
5. The reaction in which carboxylic acid reacts with alcohol in the presence of conc.H₂SO₄ to form a substance having a fruity smell.

 

(h) Fill in the blanks from the choices given in the brackets:

1. The polar covalent compound in the gaseous state that does not conduct electricity is__________. (carbon tetrachloride, ammonia,methane)
2. A salt prepared by displacement reaction is ________.(ferric chloride, ferrous chloride, silver chloride)
3. The number of moles in 11 gm of nitrogen gas is __________.(0.39, 0.49, 0.29)[atomic mass of N=14]
4. An alkaliwhich completely dissociates into ions is __________.(ammonium hydroxide, calcium hydroxide, lithium hydroxide)
5. An alloy usedto make statues is __________.(bronze, brass, fuse metal)

 

Q 2.

(a) The following table represents the elements and the atomic number.With reference to this,answer the following using only the alphabets given in the table.

1. Which element combines with hydrogen to form a basic gas?
2. Which element hasan electron affinity zero?
3. Name the element which forms an ionic compound with chlorine.

Atomic No.: Ca = 20 O= 8, Cl = 17, H =1

1. Calcium oxide
2. Chloride molecule
3. Water molecule

 

(c) Choose the correct word which refers to the process of electrolysis from A to E to match the description (i) to (iv):

A: Oxidation; B: Cathode; C:Anode; D: An electrolyte; E: Reduction

1. Conducts electricity in aqueous or in the molten state
2. Loss of electrons takes place at the anode
3. A reducing electrode
4. Electrode connected to the positive endor terminal of the battery

 

Q 3.

(a) Baeyer’s process is used to concentrate bauxite ore to alumina. Give balanced chemical equations for the reaction taking place for its conversion from bauxite to alumina.

 

(b) Complete the following by selecting the correct option from the choice given:

1. pH of acetic acid is greater than dilute sulphuric acid. So, acetic acid contains __________ concentration of H⁺ ions (greater, same, low)
2. The indicator which does not change colour on passage of HCl gas is _______(methyl orange, moist blue litmus, phenolphthalein)
3. The acid which cannot act as an oxidising agent is ________(conc. H₂SO₄, conc. HNO₃, conc.HCl)

 

(c) Match the gases given in Column I to the identification of the gases mentioned in Column II.

Q 4.

(a) Differentiate between the following pairs based on the information given in the brackets.

1. Conductor and electrolyte (conducting particles)
2. Cations and anions (formation from an atom)
3. Acid and alkali (formation of type of ions)

 

(b) Draw the structural isomers of pentane.

 

(c) Hydrogen chloride gas is prepared in the laboratory using concentrated sulphuric acid and sodium chloride. Answer the questions that follow based on this reaction:

1. Give the balanced chemical equation for the reaction with suitable condition(s) if any.
2. Why is concentrated sulphuric acid used instead of concentrated nitric acid?
3. How is the gas collected?
4. Name the drying agent not used for drying the gas.

Question 5

(a) Distinguish between the following pairs of compounds using a reagent as a chemical test:

1. Calcium nitrate solution and zinc nitrate solution
2. Ammonium sulphate crystals and sodium sulphate crystals
3. Magnesium chloride solution and magnesium nitrate solution

 

(b) Calculate the percentage of

1. Fluorine
2. Sodium
3. Aluminium in sodium aluminium fluoride [Na₃AlF₆] to the nearest whole number.[Atomic Mass: Na = 23, Al = 27, F=19]

 

(c)

1. State the volume occupied by 40 gm of methane at STP if its vapour density (VD)is 8.
2. Calculate the number of moles present in 160 gm of NaOH.[Atomic Mass: Na=23, H=1, O=16]

Q 6.

(a) Identify the salts P, Q, R from the following observations:

1. Salt P has light bluish green colour on heating. It produces a black-coloured residue. Salt P produces brisk effervescence with dil. HCl and the gas evolved turns lime water milky, but no action with acidified potassium dichromate solution.
2. Salt Q is white in colour. On strong heating, it produces buff yellow residue and liberates reddish brown gas. Solution of salt Q produces chalky white insoluble precipitate with excess of ammonium hydroxide.
3. Salt R is black in colour. On reacting with concentrated HCl, it liberates a pungent greenish yellow gas which turns moist starch iodide paper blue black.

 

(b) Identify the substance underlined in each of the following:

1. The electrode that increases in mass during the electro-refining of silver.
2. The acid that is a dehydrating as well as a drying agent.
3. The catalyst used to oxidise ammonia into nitric oxide.

 

(c) Copy and complete the following paragraph using the options given in brackets:Alkenes are a homologous series of

1. ________(saturated/unsaturated) hydrocarbons characterised by the general formula.
2. _______ (C_nH_2n+2/C_nH_2n). Alkenes undergo.
3. _________(addition/substitution) reactions and also undergo.
4. _______(hydrogenation/dehydrogenation) to form alkanes.

Q 7.

(a) Write balanced chemical equations for the preparation of the given salts (i) to (iii) by using the methods A to C, respectively:

A: Neutralisation B: Precipitation C: Titration

(i) Copper sulphate

(ii) Zinc carbonate

(iii) Ammonium sulphate

 

(b) Name the following elements:

(i) An alkaline earth metal present in group 2 and period 3.

(ii) A trivalent metal used to make light tools.

(iii) A monovalent non-metal present in fluorspar.

 

(c) An aqueous solution of nickel (II) sulphate was electrolysed using nickel electrodes. Observe the diagram and answer the questions that follow:

(i) What do you observe at the cathode and anode, respectively?

(ii) Name the cation that remains as a spectator ion in the solution.

(iii) Which equation for the reaction at the anode is correct?

1.Ni ⟶ Ni²⁺+ 2e^-

2.Ni + 2e^- ⟶ Ni²⁺

3.Ni²⁺⟶ Ni+ 2e^-

4.Ni²⁺ 2e^- ⟶ Ni

Answer 1

(a)

(i) (D) Helium

(ii) (B) Platinum

(iii) (D) Carbon tetrachloride

(iv) (C) Concentrated sulphuricacid

(v) (A) C₃H₄

 

(b)

(i) When concentrated nitric acid reacts with copper, reddish brown fumes of nitrogen dioxide are formed.

(ii) With excess of NH₄OH, the precipitate formed of Cu(OH)₂ dissolves to give a deep blue solution of tetrammine copper(II) sulphate.

(iii) A colourless, odourless gas is evolved which burns with a pop sound.

(iv)When zinc carbonate is heated strongly, carbon dioxide is evolved.

(v)Sulphide ore particles are wetted by oil and rise up with the froth, while the gangue particles are wetted by water and sink to the bottom.

 

(c)

(i) C + 4HNO₃ → CO₂+ 4NO₂+ 2H₂O

(ii) NH₃ + 3Cl₂ → NCl₃+ 3HCl

(iii) Pb(NO₃)₂+ 2NH₄OH → Pb(OH)₂ + 2NH₄NO₃

(iv)

(v) 2C₂H₆ + 7O₂ → 4CO₂+ H₂O

 

(d) (i)1.2,2-dimethyl pentane

2. Methanol

3. Isopropane

(ii) IUPAC name:

1.Acetaldehyde: Ethanal

2. Acetylene: Ethyne

 

(e)

(i) Graphite electrode being an inert electrode does not interfere in the process of electrolysis.

(ii) Sodium hydroxide absorbs moisture from the air, and therefore, soda lime (a mixture of sodium hydroxide and calcium oxide) is used as it absorbs less moisture.

(iii) Copper sulphate crystals CuSO₄.5H₂O contain 5 water molecules which are known as water of crystallisation. When we heat the crystals, these water molecules are removed and the salt turns white.

(iv) Concentrated nitric acid appears yellow when left standing in a glass bottle due to the dissolution of reddish brown nitrogen dioxide in the acid. Nitrogen dioxide is produced because of the thermal decomposition of a portion of nitric acid.

(v) When HCl gas comes in contact with moist air, it gives white fumes due to the formation of hydrochloric acid.

 

(f)

(i) 2CO+ O₂ ⟶ 2CO₂

              2 vol 1 vol 2 vol

So, 2 vol of CO₂ requires 2 vol of CO.

750 ml of CO₂ will require 2×750 ml of CO.

So, 2 vol of CO₂ requires 1 vol of O₂.

750 ml of CO₂ will require ½ ×750 ml of O₂

= 375 ml of O₂

(ii) 1 mol of gas occupies a volume of 22.4L.

1 mol of CO₂ is 44 gm.

So, 44 gm of CO₂ occupies a volume of 22.4 L at STP.

1 gm of CO₂ will occupy

80 gm of CO₂ will occupy  80 x 0.50

= 40 L

(iii) 1 mol of CO₂ contains 6.023 × 10²³ molecules.

1 mol of CO₂= 44 gm

No. of moles of CO₂ in 4.4 gm = 

0.1 mol of CO₂ contains 0.1× 6.023 × 10²³ 

= 6.023 × 10²² molecules

CO₂ contains 2 oxygen atoms, so 6.023×10²²× 2= 1.2×10²³ molecules

(iv) Law associated in question

(i) is Gay–Lussac's law of combining volumes.The law states thatwhen gases react together to produce gaseous products, the volumes of reactants and products bear a simple whole number ratio with each other provided the volumes are measured at the same temperature and pressure.

 

(g)

(i) Covalent bond

(ii )Pure copper metal

(iii) Alloy

(iv) Electronegativity

(v) Esterification

 

(h)

(i) The polar covalent compound in the gaseous state that does not conduct electricity is carbon tetrachloride.

(ii)  salt prepared by displacement reaction is ferrous chloride.

(iii) The number of moles in 11 gm of nitrogen gas is 0.39.

(iv) An alkali which completely dissociates into ions is lithium hydroxide.

(v) An alloy used to make statues is bronze.